With 6.1 million HIV-infected individuals, South Africa is an LMIC with the world's largest population of people living with HIV. To address the resulting shortages in healthcare personnel, South Africa uses a task-shifting strategy in which lay health workers provide components of HIV care. Neurocognitive impairment (NCI) is one of the most common sequelae and comorbid conditions of HIV infection and has significant medical, functional, and public health consequences. NCI affects over half of HIV-infected individuals, yet often goes undetected in the clinical setting. Although - as in other chronic diseases - routine screening for NCI in HIV can enhance provider-patient communication to promote medication adherence and positive health outcomes, it faces numerous challenges, including the need for special equipment and highly trained personnel to administer, score and interpret screening tests. Mobile technology can offer a solution to this critical public health and medical care challenge by facilitating routine screening for NCI in HIV and other chronic illnesses. To this end, we developed NeuroScreen, a brief, easy-to-use NCI screening test app for Android devices, designed to be administered by a wide range of non- expert healthcare personnel in clinical settings. The app is standardized and highly automated, requires minimal training to administer, and does not require record-keeping or scoring. It can be used in clinic exam rooms, remote rural settings, and/or home visits and requires no paper forms, stopwatches, or other equipment. NeuroScreen results are available immediately and can be transmitted electronically to a variety of end-users, such as primary care providers, HIV or other specialists, and/or electronic medical records. The proposed study will (1) adapt NeuroScreen for administration by South African, Xhosa-speaking lay counselors; (2) evaluate the counselor-administered app's sensitivity and specificity to detect NCI among 100 HIV+ adults, as well as its usability and acceptability; and (3) explore the association between NeuroScreen results and medical health outcomes - i.e., objective behavioral and biological markers of ART treatment failure. These data will be the basis for future larger-scale research on implementation and scale-up of this mHealth tool for use in LMIC settings. NeuroScreen could be easily modified for use in other diseases and LMICs that rely on task-shifting due to limited healthcare resources. This project will build research capacity in South Africa in several ways. First, our in-country collaborators and partners in developing this proposal will continue to work with us in future research based on this study. Second, this study will build the South African software developers' capacity to apply their expertise to public health and clinical research. Third, we will offer in-service trainings on NCI and mHealth tools at DOH clinics and the University of Cape Town, as well as disseminate findings and lessons learned and conduct seminars on developing and implementing mHealth research studies and tools to UCT medical and research trainees.